Bloody hell! I took out the recent replies option on the category causing trouble. I changed it from 2 to 0 and that solved the issue. I was able to activate the category again and everything is back to normal.
I'm guessing the poll was bothering the preview on the homepage.
@julian I think English is the parent repo, then translations are considered children of that one, as docs.nodebb automatically routes to /en/. That's what the documentation of your doc software says anyway. 😆